Kubota 3130 front axle fluid UDT or 80-90 SAE gear oil?

[tick magnet]

The owner's manual says I can use either UDT fluid or SAE 80-90 gear oil, with a capacity of about 7 quarts. My tractor has about 2300 mostly trouble-free hours and is 22 years old. I've always had a little UDT fluid that drips out of the left front axle area. It's low, so I have to top it off with UDT fluid, which is what I've always used, but I am wondering if switching to gear oil might be a better option for me. I'm thinking it's a bit heavier than UDT fluid and might fix the drip, drip. My understanding is that the front axle and gears are isolated from the UDT fluid I use for the hydrostatic transmission and rear differential, which is why the manual offers the option.

Thanks in advance for your response.

 

[Fedup]

It's just gears and bearings. Almost ANYTHING will work fine. Top it of with 89-90 and call it good.

 

[Wishope]

If your owner's manual specifically allows either UDT or SAE 80W-90 in the front axle, switching to 80W-90 is a reasonable option.

On many Kubota tractors, the front axle is a separate oil reservoir from the HST/rear transmission, so changing the front axle oil will not affect the UDT used elsewhere.

Because 80W-90 is thicker than UDT, it may slow a minor seep from an older axle seal. However, it won't actually repair a worn seal, so if the leak gets worse, the seal should eventually be replaced.

With 2,300 hours and only a small long-term drip, I'd drain the UDT from the front axle and refill it with the manual-approved 80W-90 rather than simply mixing the two. Then recheck the oil level after running the tractor.

As long as 80W-90 is listed in your manual, it's a perfectly reasonable choice for an older tractor with a minor front axle seep.